The present invention relates to an air conditioner using a flammable fluid as a refrigerant, and more particularly, to an air conditioner using a flammable refrigerant, especially, HC based refrigerant such as propane, isobutane and the like as a refrigerant.
HCFC based refrigerants such as R22, which are stable components and composed of hydrogen, chlorine, fluorine and carbon are currently utilized in an air conditioner.
However, HCFC refrigerants rise into the stratosphere and decompose ozone, leading to the destruction of the ozone layer.
In recent years, HFC refrigerants begin to be utilized as alternative refrigerants of HCFCs , but these HFC refrigerants have the nature for facilitating the global warming.
Therefore, a study is started to employ HC refrigerant which does not destroy the ozone layer or largely affect the global warming.
However, since this HC refrigerant is flammable , it is necessary to prevent explosion or ignition so as to ensure the safety.
As a method for preventing the explosion or ignition when HC refrigerant is used, it is proposed to isolate, move away or not to use an ignition source (Japanese Patent Applications Laid-open No.H7-55267 and No.H8-61702, for example).
On the other hand, as another method for preventing the explosion or ignition when HC based refrigerant is used, it is proposed to make the refrigerant itself into a non-flammable refrigerant (Japanese Patent Application Laid-open No.H9-59609), and it is proposed to reduce the amount of refrigerant (Japanese Patent Applications Laid-open No.H8-170859 and No.H8-170860) in the mixture.
Here, the conventional techniques (Japanese Patent Applications Laid-open No.H8-170859 and No.H8-170860) for reducing the amount refrigerant to be used will be explained in more detail.
Japanese Patent Application Laid-open No. H8-170859 and No. H8-170860 relate to a refrigerator. In order to reduce the amount of refrigerant, it is proposed: to provide a heat pipe in addition to a refrigeration cycle and to use non-flammable refrigerant for the heat pipe; to provide a refrigerant tube for heat exchangers in the compartment of the refrigerator separately from a refrigerant tube for an evaporator and to use non-flammable refrigerant for the heat pipe; to change the number of paths upstream and downstream of the evaporator or a condenser; and the like.
First, the method for preventing the explosion or ignition by isolating, moving away or not using the ignition source is very effective if the air conditioner is used alone. However, an air conditioner is used in a closed space, and other equipments may have the ignition source. Therefore, even if safety as an air conditioner may be enhanced, it can not be said that the safety is always ensured depending upon a using state.
The method for preventing the explosion or ignition by making the refrigerant itself into a non-flammable refrigerant does not have the above problem, and it can be said that safety is ensured in any of using states.
However, it is not easy to make the flammable refrigerant itself into a non-flammable refrigerant while achieving a required level of refrigerating performance without adversely affecting the global environment such as decreasing of ozone layer and global warming.
The method for reducing the refrigerant amount may not always prevent the explosion or ignition perfectly, but it contributes to effective utilization of resources. Further, even if a harmful influence may be found in the future, if the amount of refrigerant is small, such a harmful influence can be suppressed to the minimum.
Thereupon, it is an object of the present invention to technically reduce a risk of explosion or ignition and to enhance the safety by reducing an amount of refrigerant to be charged in the refrigeration cycle.
Meanwhile, if the amount of refrigerant to be charged in the refrigeration cycle is reduced without changing other conditions, since the circulation amount of refrigerant is reduced, there is a problem that cooling capacity is decreased. Further, if the compression volume is increased or the revolution number of the compressor is increased so as to prevent the cooling capacity from being decreased, there is a problem that power input is increased and the efficiency is decreased.
Thereupon, a primary object of the invention is to reduce the amount of refrigerant to be charged in the refrigeration cycle without decreasing the capacity and efficiency.
Further, a secondary object is to reduce the amount of refrigerant to be charged in the refrigeration cycle without decreasing the capacity if R290 is used as a refrigerant or mainly used as the refrigerant mixtures, while obtaining substantially the same efficiency as the case in which R22 is used as refrigerant.
An air conditioner using a flammable refrigerant according to a first aspect of the present invention, an inner diameter of a liquid-side connecting pipe is smaller than 42.5% of an inner diameter of a gas-side connecting pipe.
According to a second aspect of the invention, an inner diameter of the liquid-side connecting pipe is 1 mm to 3.36 mm.
According to a third aspect, the liquid-side connecting pipe is a capillary tube.
An air conditioner using a flammable refrigerant according to a fourth aspect, an inner diameter of a liquid-side tube of the outdoor unit is smaller than 42.5% of an inner diameter of a gas-side tube of the outdoor unit.
An air conditioner using a flammable refrigerant according to a fifth aspect an inner diameter of a liquid-side tube of the indoor unit is smaller than 42.5% of an inner diameter of a gas-side tube of the indoor unit.
According to a sixth aspect, an inner diameter of the liquid-side tube of the fourth or fifth aspect is 1 mm to 3.36 mm.
According to a seventh aspect, the liquid-side tube of the fourth or fifth aspect is a capillary tube.
A refrigeration cycle using a flammable refrigerant according to an eighth aspect, an inner diameter of a liquid-side tube of the tube is smaller than 42.5% of an inner diameter of a gas-side tube.
According to a ninth aspect, an inner diameter of the liquid-side tube is 1 mm to 3.36 mm.
A refrigeration cycle using a flammable refrigerant according to a tenth aspect, a liquid-side tube among the tubes is a capillary tube.
An air conditioner using a flammable refrigerant according to an eleventh aspect, an inner diameter of a liquid-side connecting pipe among the connecting pipes is 1 mm to 3.36 mm.
A refrigeration cycle using a flammable refrigerant according to a twelfth aspect, an inner diameter of a liquid-side tube among the tubes is 1 mm to 3.36 mm.
According to the first to twelfth aspects of the present invention, by reducing a diameter of the tube in which a liquid refrigerant flows in the air conditioner or the refrigeration cycle, it is possible to reduce the amount of refrigerant to be charged without decreasing the capacity and the efficiency.
An air conditioner using a flammable refrigerant according to a thirteenth aspect, a liquid-side connecting pipe is a capillary tube, and the expansion device is an expansion valve having a variable flow rate.
According to this aspect, an opening of the expansion valve can be-adjusted by the expansion valve in accordance with a length or diameter of the liquid-side connecting pipe or a state of a refrigeration cycle. Therefore, it is possible to reduce the diameter of the liquid-side connecting pipe, and since the throttle degree can be adjusted by the expansion valve, the diameter can be reduced appropriately, and it is possible to reduce the amount of refrigerant to be charged without decreasing the capacity.
An air conditioner using a flammable refrigerant according to a fourteenth aspect, not only the liquid-side tube of the outdoor unit, but also the liquid-side tube of the indoor unit is provided with an expansion device. Since the liquid-side tube of the indoor unit is also provided with the expansion device in this manner, the refrigerant in the liquid-side connecting pipe can assume a two phase state of gas and liquid during heating operation and therefore, it is possible to reduce the amount of refrigerant to be charged as compared with a liquid refrigerant, and the capacity and the efficiency are not decreased.
A refrigeration cycle using a flammable refrigerant of a fifteenth aspect, an inner diameter of an outlet side tube of the condenser is smaller than an inner diameter of an inlet side tube of the condenser.
According to a sixteenth aspect, the inner diameter of the outlet side tube of the condenser of the fifteenth aspect is less than 42.5% of the inner diameter of the inlet side tube of the condenser.
According to a seventeenth aspect, the inner diameter of the outlet side tube of the condenser of the fifteenth aspect is 1 mm to 3.36 mm.
According to the fifteenth to seventeenth aspects, by reducing a diameter of the tube in which a liquid refrigerant flows in the condenser, it is possible to reduce the amount of refrigerant to be charged without decreasing the capacity and the efficiency.
According to an eighteenth aspect, the number of circuits of the outlet side tubes of the condenser of the fifteenth to seventeenth aspects is greater than that of the inlet side tubes. Although the pressure loss is increased due to a reduction in the diameter, if the tube in which the liquid refrigerant flows is diverged in this manner, the pressure loss can be reduced. Therefore the diameter can be reduced, and the amount of refrigerant can further be reduced.
According to a nineteenth aspect, the inner diameter of the outlet side tube of the condenser of the fifteenth aspect is reduced stepwisely.
According to a twentieth aspect, the inner diameter of the outlet side tube of the condenser of the nineteenth aspect is gradually reduced such that a temperature is changed along a saturated liquid line.
An air conditioner using a flammable refrigerant of a twenty first aspect, the number of circuits of a liquid-side tube of the indoor heat exchanger or the outdoor heat exchanger is greater than that of a gas-side tubes, and when the indoor heat exchanger or the outdoor heat exchanger is functioned as a condenser, the number of circuits of the liquid-side tube is reduced. When indoor heat exchanger or the outdoor heat exchanger is functioned as the condenser in this manner, it is possible to reduce the residence of refrigerant by reducing the number of circuits of the liquid-side tubes. When the outdoor heat exchanger is functioned as an evaporator, the pressure loss around the inlet of the evaporator can be reduced by increasing the number of circuits, and it is possible to efficiently operate the air conditioner.
According to twenty second and twenty third aspects, R290 is used as a main component of the flammable refrigerant mixture in the first, fourth, fifth, eighth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth or twenty first aspect. If R290 refrigerant is compared with R22 refrigerant, since a latent heat of R290 is 1.8 times of that of R22, in order to obtain the same ability, the pressure loss of R290 is 70% of that of R22 if the diameters of the tube are the same. Therefore, the pressure losses of both the refrigerants are equalized, the diameter of tube can be reduced and the amount of refrigerant to be charged can be reduced if R290 refrigerant is used as compared with a case where R22 refrigerant is used.
In the following twenty fourth to thirtieth aspects, the amount of refrigerant to be charged is reduced by reducing a diameter of a tube in which the gas refrigerant flows. At that time, if a diameter of the gas-side tube is reduced, the efficiency is decreased, but comparing with a case in which R22 is used as refrigerant, the efficiency is enhanced if R290 is used as refrigerant. Therefore, paying attention to pressure losses of the R22 and R290 in the present aspect, the diameter of the gas-side tube is reduced such that the pressure losses between R22 and R290 become same.
The inner diameter of the tube when R290 is used such that both the pressure losses becomes equal is 90 to 92% of the inner diameter of the tube when R22 is used. The conventionally used gas-side tube when R22 is used as refrigerant is xe2x85x9c inch tube and xc2xd inch tube. Therefore, the inner diameter of the gas-side tube corresponding to a case in which R290 is used based on xe2x85x9c inch tube is 7.13 to 7.29 mm, and by setting the inner diameter of the gas-side tube in this range, the same efficiency as a case in which R22 is used as refrigerant can be obtained. Further, since the diameter of the tube can be reduced less than the conventionally used gas-side tube, it is possible to reduce the amount of refrigerant to be charged.
An air conditioner using a flammable refrigerant of the twenty fourth aspect, an inner diameter of a gas-side connecting pipe is 7.13 to 7.29 mm, and an inner diameter of a liquid-side connecting pipe is less than 66.6% of the inner diameter of the gas-side connecting pipe.
According to twenty fifth aspect, the liquid-side connecting pipe of the twenty fourth aspect is a capillary tube.
An air conditioner using a flammable refrigerant according to a twenty sixth aspect, an inner diameter of a gas-side tube of the outdoor unit is 7.13 to 7.29 mm, and an inner diameter of a liquid-side tube is less than 66.6% of the inner diameter of the gas-side tube.
An air conditioner using a flammable refrigerant according to a twenty seventh aspect, an inner diameter of a gas-side tube of the indoor unit is 7.13 to 7.29 mm, and an inner diameter of a liquid-side tube is less than 66.6% of the inner diameter of the gas-side tube of the indoor unit.
According to a twenty eighth aspect, the liquid-side tube of the twenty sixth or twenty seventh aspect is a capillary tube.
A refrigeration cycle using a flammable refrigerant according to a twenty ninth aspect, an inner diameter of a gas-side tube of the tubes is 7.13 to 7.29 mm, and an inner diameter of a liquid-side tube is less than 66.6% of the inner diameter of the gas-side tube.
A refrigeration cycle using a flammable refrigerant according to a thirtieth aspect, an inner diameter of a gas-side tube of the tubes is 7.13 to 7.29 mm, and a liquid-side tube is a capillary tube.
According to the following thirty first to thirty third aspect, a diameter of the connecting pipe is reduced so as to reduce the amount of refrigerant to be charged.
A connecting pipe for an air conditioner of the thirty first aspect, an inner diameter of a liquid-side connecting pipe is less than 42.5% of an inner diameter of a gas-side connecting pipe.
A connecting pipe for an air conditioner of the thirty second aspect, an inner diameter of a liquid-side connecting pipe is 1 mm to 3.36 mm.
A connecting pipe for an air conditioner of the thirty third aspect, an inner diameter of a gas-side connecting pipe is 7.13 mm to 7.29 mm, and an inner diameter of a liquid-side connecting pipe is less than 66.6% of the inner diameter of the gas-side connecting pipe.